150 PROCKEDINGS OF THE GEOLOGICAl SOCIETY. [Feb. 7, 



passed westwards as far as the hilly ground of Devonshire, running 

 out between Wales and Devonshire through what is now the Bristol 

 Channel. The whole of the middle of England was likewise covered by 

 the same deposits, viz. the plains of Shropshire, Cheshire, Lancashire, 

 and the adjoining areas ; so that the Lias and Oolites passed out to 

 what is now the Irish Sea, over and beyond the present estuaries of 

 the Dee and the Mersey, between North Wales and the hilly ground 

 of Lancashire, formed of previously disturbed Carboniferous rocks. 

 In brief, most of the present mountainous and hilly lands of the 

 mainland of Britain were mountainous and hilly then, and even 

 higher than now, considering how much they must since have suf- 

 fered by denudation. 



At this period, south of the Derbyshire hills and through Shrop- 

 shire and Cheshire, the Lower Secondary rocks lay somewhat flatly ; 

 while in the more southern and eastern areas they were tilted up 

 to the west, so as to give them a low eastern dip. The general 

 arrangement of the strata in the south would then be somewhat as 

 shown in fig. 2 (p. 151). 



The submersion of this low-lying area brought the deposition of 

 the Wealden strata to a close, and the Cretaceous formations were 

 deposited above the Wealden and Oolitic strata, so that a great un- 

 conformable overlap of Cretaceous strata took place across the 

 successive outcrops of the Oolitic and older Secondary formations, 

 as shown in fig. 3 (p. 151). 



The same kind of overlapping of the Cretaceous on the Oolitic 

 formations took place at the same time in the country north and 

 south of the present estuary of the Humber, the proof of which is 

 well seen in the unconformity of the Cretaceous rocks on the Oolites 

 and Lias of Lincolnshire and Yorkshire. 



At this time the mountains of Wales and other hilly regions 

 formed of Palaeozoic rocks must have been lower than they were 

 during the Oolitic epochs, partly by the efiect of long- continued 

 waste, due to atmospheric causes, but probably even more because 

 of gradual and greatly increased submergence during the time that 

 the Chalk was being deposited. I omit any detailed mention of the 

 phenomena connected with the deposition of the freshwater and 

 marine Eocene strata, because at present this subject does not seem 

 essential to my argument. 



The Miocene period of old Europe was essentially a continental 

 one. Important disturbances of strata brought this epoch to a close, 

 at all events physically, in what is now the centre of Europe ; and 

 the formations formed in the great freshwater lakes that lay at the 

 bases of the older Alps were, after consolidation, heaved up to form 

 new mountains along the flanks of the ancient range ; and all the 

 length of the Jura, and far beyond to the north-west, was elevated 

 by disturbances of the Jurassic, Cretaceous, and Miocene strata. The 

 broad valley of the lowlands of Switzerland began then to be estab- 

 lished, subsequently to be overspread by the large glaciers that 

 deepened the valleys and scooped out the lakes. 



One marked efiect of this extremely important elevation, after 

 Miocene times, of so much of the centre of Europe was, that the flat 



